Total number of hydrogen molecules required to form ethane from ethyne is

Options

A. One
B. Two
C. Three
D. Four

Answer

To determine the total number of hydrogen molecules required to form ethane (C2H6) from ethyne (C2H2), we can follow these steps:

### Step 1: Write the chemical formulas
- Ethyne (acetylene) is represented as C2H2.
- Ethane is represented as C2H6.

### Step 2: Understand the reaction
To convert ethyne (C2H2) to ethane (C2H6), we need to add hydrogen (H2) molecules. The reaction can be summarized as follows:

\[ \text{C}_2\text{H}_2 + \text{H}_2 \rightarrow \text{C}_2\text{H}_6 \]

### Step 3: Determine the number of hydrogen atoms needed
- Ethyne has 2 hydrogen atoms (C2H2).
- Ethane has 6 hydrogen atoms (C2H6).
- Therefore, to convert ethyne to ethane, we need to add 4 hydrogen atoms.

### Step 4: Calculate the number of hydrogen molecules
Since each hydrogen molecule (H2) contains 2 hydrogen atoms, we can calculate the number of hydrogen molecules required:

\[ \text{Number of H}_2 \text{ molecules} = \frac{\text{Total hydrogen atoms needed}}{2} = \frac{4}{2} = 2 \]

### Conclusion
Thus, the total number of hydrogen molecules required to form ethane from ethyne is **2**.

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